Cities should allow and even promote dockless rental scooters. The scooters have the following benefits:
1. They are electric and therefore compatible with the move away from fossil fuels
2. They allow people who don't/can't own cars to have a means of transportation, Including people with disabilities and low-income people
3. They are convenient
4. They are a more effective way of getting around a dense urban area than an automobile
5. They cause no harm and pose no danger

I shall oppose your motion by answering your claims.
"They are electric and therefore compatible with the move away from fossil fuels"
Hence the problem. The fact is, While electric is the option for the future, Its compatibility, Particularly cost compatibility throws it into question. As the topic suggests, You wish for rental scooters at a time when people with cars are using them already, And people without them are turning to public transportation. Again, It is not that this avenue has NOT been explored, But the investment and reclaiming potential for electric rental scooters cannot be expected to be at a match. You see, We need high investment, And scooters for rent are not as viable as rent-a-cars.

"They are convenient. "
Convenience is not a gold standard to measure the viability of a transport proposal. Scooters are slower than cars. They transport far less people than a car could. Also, Scooter parking spots are very few compared to cars, And hence they face a major parking challenge. In fact, People are turning to public transportation for efficacy - people want efficiency more than anything else.

"They are a more effective way of getting around a dense urban area than an automobile"
This is precisely a problem in countries like Bangladesh and Indonesia, Where the Too Many People, Too Less Area paradox can be seen (name has been set by me, And hence kindly do not consider this as a sourced fact). Motorcycles, Bikes and scooters clog roads and cause blocks for bigger cars to pass. As a result, The quality of transport has reduced. Since the topic did not include any demographic specification, How can we expect the scooter to even contribute to the traffic situation in such countries?

"They cause no harm and pose no danger"
Yet again, Scooters are in fact more prone to cause harm. You see, Because they fit into small spaces, This phenomenon is especially widespread in Asia, Where the traffic system is substandard. As a former resident in an Asian country, Scooters just clog up zebra crossings, Hence leaving pedestrians exposed to accident. Even in America, The NHTSA recorded 92, 000 injuries 4295 deaths from mopeds and scooters for 2014.

I rest my case. Electric rental scooters cannot be expected to replace the modes of transport we already have. The floor is yours now.